Waveguide



March M, 196'? W. KRANK Eff-AL WAVEGUIDE Filed May 5, 1965 NVENTRS 7TTORNEYS United States Patent O 3,309,627 WAVEGUIDE Wolfgang Krank andErich Schiittltel, Backnang, Germany, assignors to TelefunkenPatentverwertungsgesellschaft m.b.H., Ulm (Danube), Germany Filed May 5,1965, Ser. No. 453,384 Claims priority, application Germany, May 5,1964,

11 Claims. (Cl. 333-21) The present invention relates generally to themicrowave art, and, more particularly, to a waveguide which is capableof being wound onto a drum.

Arrangements of corrugated waveguides having cross sections which areother than circular are already known. These arrangements are soconstructed that a defined reference plane is provided with respect tothe mechanical and electrical characteristics of the waveguide so thatconnection elements can be connected to the reference plane by anges orthe like. The disadvantage of such an arrangement is that a waveguidesupporting structure and a transition are required and these structures,because of their cross-sectional forms are very expensive. Inconventional arrangement, the necessary electrical connection isprovided by suitably shaped shells which are semicircular in crosssection, or other connecting elements which surround the waveguide andare positively locked together with the housing of the arrangement. Thistype of construction requires a rather expensive and spaceconsumingmounting.

With this in mind, it is a main object of the present invention toprovide a waveguide arrangement which eliminates the above-mentioneddisadvantages without adversely inliuen-cing the electricalcharacteristics.

Another object of the invention is to provide a waveguide arrangement ofthe character described wherein the length of the structural elementscan be decreased.

These objects and others ancillary thereto are accomplished inaccordance with preferred embodiments of the invention wherein acorrugated waveguide of circular or non-circular cross section isprovided with a hollow body inside the waveguide. The hollow body isIfashioned so as to be outwardly resilient or have spring to it at leastat its inner end and is so inserted into the waveguide that theelectrical connections take place in the region of the springy portionof the hollow body. The non-resilient end of the hollow body ispositively connected to the waveguide.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a longitudinal sectional view illustrating one embodiment ofthe present invention.

FIGURE 2 is a transverse sectional view taken generally along the planedefined by reference line 2-2 of FIGURE 1.

FIGURE 3 is .a longitudinal sectional View similar to FIGURE 1 butillustrating another embodiment of the present invention.

FIGURE 4 is a longitudinal sectional view similar to FIGURE 3 but usinga capacitive short-circuit.

With more particular reference to the drawings, FIG- URES 1 and 2illustrate an arrangement for a corrugated waveguide 1 which, forexample, has an elliptical cross section. The end 2 of this waveguideportion is provided with a flange. This tlange end 2 is retained inposition between a reinforcing or securing ange 3 and clamping jaws 1t).The flange 3 and jaws 10 are retained in position by means of boltedjoints (not shown).

A hollow body 4 extends axially into the corrugated waveguide section 1.This body serves for -contacting pur- 3,309,527 Patented Mar. 14, 1967poses or for connections between a transmission line and the waveguide,and is connected to the tiange 3 by soldering 9. This body which isprovided `for connecting purposes is arranged to be springy on the endwhich faces away from flange 3. The spiinginess is provided in theembodiment shown in FIGURES 1, 2 by slots 5, cut into the ends thereof.

Energy can be coupled in and out of the waveguide 1 by a couplingelement which can be laterally inserted into the end of the waveguideand which may be in the orm of a cross bar. In the embodimentillustrated the Coupling member includes a metal rod 7 arranged parallelto the major axis of the waveguide and which is conductively orgalvanically connected to the waveguide walls at its ends. The middle ofrod 7 is provided with an enlargement 8 and at this point a metallicmember 6 is arranged at right angles to rod 7. Metallic element 6represents the inner conductor of a coaxial line `for coupling energyinto and out of the waveguide.

The outer conductor of such coaxial line is represented by a metalelement 11 which is a semi-circle in cross section and provided with anopening 11a through which the inner conductor 6 may pass. The innerconductor 6 is supported in the opening 11a by means ot an insulateddisk 12. A dielectric coating 13 is provided for protecting thewaveguide. Another portion which is complementary to portion 11 andwhich is also semicircular is section 14 which together with portion 11annularly surrounds the waveguide.

The axis of rod 7 arranged at right angles to the length of thewaveguide is disposed at a distance )J1/4 from the short circuit planewhich is formed by the inner surface of flange 3, and where AHrepresents the waveguide length.

From FIGURE 2 it can be seen that the rod 7 is provided with recessesalong the length thereof to provide a particularly large bandwidth.

FIGURE 3 shows a further embodiment wherein elements which are similarto those of FIGURES 1 and 2 are provided with similar reference numeralsbut with primes added. In this arrangement the waveguide 1 is providedwith a springy hollow body 4 provided with slots at its end, but thehollow body is arranged as an extension of the liange 3. This tlange 3has a recess which is used for coupling energy into and out of thewaveguide. The coupling opening 15 can, Ifor example, have a rectangularcross section corresponding to the normal Icross section yforrectangular waveguides. Assuming that the waveguide 1' is provided withan elliptical cross section, this means that the hollow body 4 disposedin the corrugated waveguide at the same time serves as a transitionpiece for the two dilerent waveguide cross sections. The remainder ofthe structure is similar to that of the previously-described embodiment,except that the energy is coupled out at the end of the waveguidesection.

It can thus be seen that the construction provided by the presentinvention yields many advantages since that portion of the arrangementwhich is disposed outside of the waveguide can be made considerablysmaller than previously since it only serves as supporting means for theelement which is inserted. The conventionally used junction element iseliminated. The advantages of the present invention become particularlyapparent when winding the waveguide on a drum. The end of the hollowbody which has spring to it and which is inserted into the waveguide forconnecting purposes is suitably cut to be oblique so as to correspond tothe corrugation pitch. In this case, the springy end has at least thelength of one pitch of the corrugations of the waveguide. The springeect is, for example, produced by providing elongated slots in the freeend of the hollow body so that the so produced spring portions arerolled outwardly in a manner which depends upon the required contactpressure. The

"conventionally connected vwith the' anged or free end of a waveguide.The end of the waveguide is closed in this v'arrangement and this hasgreat' advantages during transportation because it prevents thewaveguide end from becoming damaged.

Coupling energy into and out of the waveguide can be performed in thezone between the springy end and the remote end of the hollow body. Forthis purpose, suitable openings can be formed in order to connect thenecessary coupling elements. These openings can be easily sealed fortransporting the device. The coupling can be provided lby inserting thecoupling element laterally into the waveguide end or by connecting thecoupling elements through a corresponding opening in the end plate.

If the coupling is performed through the end plate (socalled finalcoupling) the plastic coating which is always used in such waveguidescan remain on the waveguide up to the ends thereof during mounting ofthe arrangement because the formation of the mechanical contact betweenthe arrangement and the end of the waveguide requires only very littlespace. The stop plate itself and the supporting zone are advantageouslyprotected against corrosion by a dielectric layer applied after mountingis accomplished. j

Coupling element means is in the broader sense an element which makespossible the coupling inor coupling out of electromagnetic energy suchas a pin, loop, or coupling opening.

The hollow body 4 usually consists of a springy material like bronze.The projecting strips which remain after the slotsS are cut would begiven an initial outward deformation so that they would have to besprung inwardly in order to be inserted into the waveguide. Thespringiness allows a good mechanical contact of the body 4 with'thewaveguide. Contact will be made only with the springy end of body 4fInstead of .producing the above-mentioned'electrical connection'withinthe waveguide by mechanically connecting the hollow body, which isdesigned to be correspondingly flexible, the electrical contact can alsobe provided in an equivalent manner by a capacitive short circuitbetween the waveguide and the hollow body.

FIGURE 4 shows an embodiment similar to FIGURE 3 but using a capacitiveshort-circuit. The hollow body 4, which is springy, too, has adielectric coating 16. The dielectric material and the thickness b areso chosen as to give thedesired'short-circuiting for the transmittedwaves inthe waveguide. i

It will be understood that the above description of the so thatelectrical connections can be provided in the springy portion of thehollow' body, and the other end of the hollow body being firmlyconnected with the waveguide, the springy end of the hollow body beingoblique with respect to the longitudinal axis of the waveguide so as tocorrespond to the corrugation pitch of the waveguide and the springy endhaving at least the length of one pitch of ,the corrugati'on.

2. An arrangement as defined in claim 1 wherein said other end of thehollow body is an end plate vfor the waveguide. y I

3. A waveguide arrangement, comprising, in combination:

a flexible waveguide capable of being wound upon a drum;

a hollow body disposed in one end of the waveguide and having only itsinward portion outwardly springy, said body being inserted into thewaveguide so that the electrical connections can -be provided in thespringy portion of the hollow body; and

means for firmly connecting the other end of the hollow body with thewaveguide.

4. An arrangement as defined in claim 3 wherein an electrical contact isprovided between one end of the hollow body and the waveguide by meansof a capacitive short circuit.

5. An arrangement as defined in claim 3 comprising connecting means forcoupling energy into and out of the waveguide and connected in theregion between the springy portion and the other end of the hollow body.

6. An arrangement as defined in claim 5 wherein said connecting -meansincludes a. coupling element inserted laterally into the end ofthewaveguide. 7. An Varrangement as defined in claim 5 wherein said otherend of the hollow body is an end plate for the waveguide.

8. An arrangement as defined in claim 7 wherein the connecting meansincludes an element which passes through the stop plate.

9. An arrangement as defined in claim 5 comprising an end plate on saidwaveguide, said other end of the hollow body being connected to said endplate.

10. A waveguide arrangement, comprising, in combination:

a liexible waveguide capable of being wound upon a drum; and v a hollowbody disposed in an end of the waveguide and having only its inwardportion outwardly springy, said body being inserted into the waveguideso that the electrical connections can be provided in the springyportion of the hollow body, and the other end of the hollow body beingfirmly connected with the waveguide.

11. An arrangement of a waveguide capable of being wound 4on a drum,comprising, in combination:

a waveguide tubewhich is exible so as to be capable of being 4wound on adrum; and

a hollow body of suitable cross section disposed in said tube, saidhollow body being arranged so as to have spring in an outward directionand being inserted into the waveguide tube so that electrical connectingtakes place in the vicinity of the springy portion of the hollow body,the non-springy end of the hollow body being positively connected withthe waveguide.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner` L. ALLAHUT, Assistant Examiner.

10. A WAVEGUIDE ARRANGEMENT, COMPRISING, IN COMBINATION: A FLEXIBLEWAVEGUIDE CAPABLE OF BEING WOUND UPON A DRUM; AND A HOLLOW BODY DISPOSEDIN AN END OF THE WAVEGUIDE AND HAVING ONLY ITS INWARD PORTION OUTWARDLYSPRINGY, SAID BODY BEING INSERTED INTO THE WAVEGUIDE SO THAT THEELECTRICAL CONNECTIONS CAN BE PROVIDED IN THE